Conventionally, a caliper disk brake includes a brake disk having an axis of rotation, a brake caliper, a back plate assembly, a force transmission element, such as a brake-pad plate and/or a pressure plate (which is guided and supported in a channel of the brake caliper or the back plate assembly), a hold-down spring for holding down the force transmission element and a hold-down device, which is held and supported on the caliper by a holding device having a centerline lying parallel to the axis of rotation. The hold-down device pre-stresses the hold-down spring radially against the force transmission device and pre-stresses the hold-down spring against the force transmission device tangentially in the direction of rotation in forward travel of the vehicle. Brakes of this general type under consideration are disclosed, for example, in EP 694 707 B3. A characteristic feature of such brakes is the axial offset of the hold-down yoke by way of an eccentric interlocking support in the brake caliper, in order to exert not only radial but also tangential pre-stressing on the brake linings via the positively interlocking engagement in the hold-down springs formed for this purpose.
The basic principle of radial and tangential pre-stressing has proved its worth and should be retained. However, there is a need for design and functional modifications to the brake caliper and to the relevant parts of the hold-down system to afford greater efficiency and greater versatility.
FIGS. 1 and 2 herein show the brake according to EP 694 707 B3. FIG. 1 shows a brake lining 11, which is guided and supported radially inwards and on both sides in a circumferential direction in a channel guide of the brake caliper or back plate assembly, and on the radially outer edge of which lining a hold-down spring is supported, which is symmetrically formed to both sides of its center axis. Centrally, the hold-down spring comprises a radially deeper center area 3, from which the higher spring legs 6, 7 extend outwards on both sides along the outer edge of the lining, in order for the ends to then exert a spring action on the brake lining when a likewise symmetrically formed hold-down yoke 1 engages with a positive interlock in the here radially inward formed center area.
The hold-down yoke 1 is formed from round material. The spring pre-stressing occurs when the hold-down yoke 1, as in FIG. 2, is anchored on the actuation side in interlock openings of the brake caliper, and on the other side is then fixed firmly but detachably by means of bolts to a bearing block of the brake caliper on the wheel-rim side. The hold-down yoke extends over a caliper opening serving for the fitting/removal of brake linings, supported on both sides of the brake disk, and in a direction towards the brake or center axis A.
In the axial direction of the brake linings, the hold-down springs are coupled to the brake lining, because radial shoulders 12, 14 of the outer edge of the brake lining pass through elongated openings 8, 9, 10 in the spring. At the ends, the spring legs bear against further radial shoulders 13, 13 of the outer edge of the brake lining. The hold-down springs are embodied as leaf springs.
The radial and tangential pre-stressing acting on the brake lining by means of the hold-down spring is generated in that the hold-down yoke 1 engages with a positive interlock in the radially formed center area 3 of the hold-down spring and in turn is supported by positive interlock in actuation and wheel rim-side anchorages of the brake caliper, always offset towards the brake disk run-out side by an axial offset x relative to the center or brake axis A, in the direction of rotation of the brake disk in forward travel. As a result, the corresponding spring leg is also forced in a tangential direction. For the eccentric positively interlocking support of the hold-down yoke 1, the requisite design shapes must be provided at corresponding positions in the brake caliper casting, and these design shapes then still have to undergo machining operations. The bearing points for the hold-down yoke 1 are therefore formed asymmetrically on/in the brake caliper.
The relevant brakes are fitted on both sides of the axle, so that they too need to be of mirror-symmetrical design. This means that different casting pattern designs are required for a left-hand brake and a right-hand brake in order to produce the asymmetrical support and holding areas. Accordingly, the positions of the subsequent machining operation for the support and holding areas in the case of a left-hand brake are different from those in that of a right-hand brake.
Owing to the aforementioned asymmetry, this principle with different caliper designs is an obstacle to economic and cost-efficient production of the brake calipers mass-produced by casting and machining.